<!DOCTYPE html>
<html>
	<head>
		<meta charset="UTF-8">
		<title></title>
	</head>
	<body>
	</body>
	<script type="text/javascript">
		//正常数组
		var a=Array.apply(null,{length:3});
		console.log(a);
		a.map(function(v,i){console.log(i)})
		
		//稀疏数组
		var b=new Array(3);
		console.log(b);
		b.map(function(v,i){console.log(i)})
		
		
		
	</script>
</html>
